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Helicoverpa armigera is an universal pest around the world, which has recovered again in recent years because of the adjustment of cropping structure and resistance to Bacillus thuringiensis (Bt) in China. As a new insecticide spinetoram is extensively used to control many pest insects, including H. armigera. However the lethal and sublethal effects of spinetoram on cotton bollworm have not been assessed. In the present study, the toxicity of spinetoram against cotton bollworm was tested under laboratory conditions. Results demonstrated spinetoram showed an excellent activity against H. armigera, especially, against Bt (Cry1Ac) resistant H. armigera. Treatment with spinetoram at the doses of 0.19 mg/kg and 0.36 mg/kg (LC8 and LC20 after 24h oral exposure) significantly arrested the development of surviving larvae and caused significant decrease in larvae wet weight. Besides, the survivors after spinetoram treatments showed significant reduction of pupation ratio, pupal weight, emergence ratio, longevity and fecundity of adults. At same time, spinetoram treatments resulted in significant increase in the prepupal and pupal periods of survivors. In summary, these results showed that spinetoram could be used as an effective pesticide to control H. armigera, especially Cry1Ac-ressitacne, consequently to take both lethal and sublethal effects to cotton bollworm into consideration in cotton bollworm control strategy.

Developing oocytes accumulate plentiful yolk protein during oogenesis through receptor-mediated endocytosis. The vitellogenin receptor (VgR), belonging to the low-density lipoprotein receptor (LDLR) family, regulates the absorption of yolk protein. In this work, the full-length vitellogenin receptor (HaVgR) in the cotton bollworm Helicoverpa armigera was identified, encoding a 1817 residue protein. Sequence alignment revealed that the sequence of HaVgR contained all of the conservative structural motifs of LDLR family members, and phylogenetic analysis indicated that HaVgR had a high identity among Lepidoptera and was distinct from that of other insects. Consistent with other insects, HaVgR was specifically expressed in ovarian tissue. The developmental expression pattern showed that HaVgR was first transcribed in the newly metamorphosed female adults, reached a peak in 2-day-old adults and then declined. Western blot analysis also revealed an ovarian-specific and developing expression pattern, which was consistent with the HaVgR mRNA transcription. Moreover, RNAi-mediated HaVgR knockdown strongly reduced the VgR expression in both the mRNA and protein levels, which inhibited the yolk protein deposition in the ovaries, led to the dramatic accumulation of vitellogenin and the up-regulation of HaVg expression in hemolymph, and eventually resulted in a declined fecundity. Together, all of these findings demonstrate that HaVgR is a specific receptor in uptake and transportation of yolk protein for the maturation of oocytes and that it plays a critical role in female reproduction.

The common cutworm, Spodoptera litura (F.), is a serious crop pest with a strong migratory ability. Previous studies on the migration of S. litura were mostly carried out in its "year-round breeding region" (YBR) or "overwintering region" (OR). However, the pattern of seasonal movements in its "summer breeding region" (SBR; i.e., northern China where they cannot overwinter) remains unknown. Here, we present data from an 11-yr study of this species made by searchlight trapping on Beihuang (BH) Island in the center of the Bohai Strait, which provides direct evidence that S. litura regularly migrates across this sea. There was considerable yearly and monthly variation in the number of S. litura trapped on BH, with the vast majority trapped in the autumn. The mean time from the earliest trapping to the latest trapping within a year was 110 ± 12 d during 2003-2013, with the shortest time span of 40 d in 2003 and the longest of 166 d in 2012. S. litura moths had downwind displacement rather than randomly by heading toward their seasonally favorable direction (i.e., toward southwest in the four autumn migration events by prevailing northeasterly winds). Some females trapped in July showed a relatively higher proportion of having mated and a degree of ovarian development, suggesting that the migration of this species is not completely bound by the "oogenesis-flight syndrome." These findings provide a good starting point of research on S. litura migration between its OR (or YBR) and SBR, which will help us develop more effective regional management strategies against this pest. [ABSTRACT FROM AUTHOR]